1. Field of the Invention
The present invention relates to an electric parking brake. More particularly, the present invention relates to an electric parking brake capable of reducing the space occupied by a spindle as well as the length of the spindle by fixing a stopper member to an outer circumferential surface of the other end of the spindle, instead of one end of the spindle linked with a parking cable, such that a parking cable is pulled into a screw nut when a brake operates.
2. Description of the Related Art
In general, vehicle brakes are classified into a foot brake pressed by a foot and a hand brake manipulated by a hand. Parking brakes are also classified into a foot brake type and a hand brake type.
When a driver pulls up a parking brake lever or steps on a pedal after parking a vehicle, a pulley rotates so that a cable linked with the pulley is pulled, thereby operating the parking brake. Accordingly, the parking brake prevents the vehicle in a stationary state from moving by external force. In addition, even if the vehicle is parked on a slope road, the parking brake prevents the vehicle from sliding down along the slope road.
However, in such a manual parking brake, the driver must pull up the parking lever with suitable force. In addition, the parking brake lever has a large operational radius, so space utility in the vehicle may be degraded.
In order to overcome such disadvantages of the manual parking brake, recently, an electric parking brake has been suggested to automatically operate a brake using a motor. Various research and development have been performed to improve the operational performance of the electric parking brake or reduce operational noise thereof.
As shown in FIGS. 1 and 2, the electric parking brake includes a motor 1, multi-stage gears 2, a gear wheel 3, a screw nut 4, a spindle 5, a parking cable 6, and a stopper member 7. The motor 1 forms torque through an electric device. The multi-stage gears 2 are coupled with the motor 1. The gear wheel 3 is mechanically linked with the multi-stage gears 2. The screw nut 4 has a hollow structure, and is integrally formed with an inner circumferential surface of the gear wheel 3. The spindle 5 is geared with the inner circumferential surface of the screw nut 4 to move in a shaft direction according to the rotation of the gear wheel 3. The parking cable 6 is linked with the spindle 5 at an outlet side of the spindle 5 (that is, the operational side of the parking cable 6). The stopper member 7 is fixed to an outer circumferential surface of the spindle 5, which is a coupling part between the spindle 5 and the parking cable 6, to prevent the spindle 5 from rotating due to excessive pulling of the spindle 5 when the brake is operated.
As shown in FIG. 1, in the parking braking having the above structure, if power is applied to the motor 1, the motor 1 is driven, and then the multi-stage gears 2 are rotated at a rotation speed reduced by a reduction gear set provided in a gear box due to the driving of the motor 1. Then, the gear wheel 3 engaged with the multi-stage gears 2 is rotated. Subsequently, the screw nut 4, which has a hollow structure and is integrated with the inner circumferential surface of the gear wheel 3, is rotated. As the screw nut 4 is rotated, the spindle 5 screwed with the screw nut 4 therein is moved as shown in FIG. 2. Then, the parking cable 6, which is linked with the spindle 5 at the outlet side (the operational side of the parking cable 6) of the spindle 5, that is, one end of the spindle 5 remote from the gear wheel 3, is pulled. If the parking cable 6 is fully pulled, the spindle 5 is prevented from rotating by the stopper member 7 fixed to the outer circumferential surface of the end of the spindle 5 linked with the parking cable 6.
However, in the electric parking brake having the above structure, since the stopper member 7 is fixed to the outer circumferential surface of the end of the spindle 5 linked with the parking cable 6, the spindle 5 is moved toward the outlet side (the operational side of the parking cable) when braking is released as shown in FIG. 1. Therefore, the spindle 5 must have a long length. As a result, the spindle 5 occupies an excessive space, and the manufacturing cost of the spindle 5 is increased.